<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script type="text/javascript">
    let arr1 = [1,2,3];
    let arr2 = [5,6,7];

    let arr = [...arr1, ...arr2];

    alert(arr);
  
    </script>
  </head>
  <body>

  </body>
</html>
